Magnetic Device for Performing a Logic Function

1. A device for performing a “logic function” including a magnetic structure comprising: at least one first magnetoresistive stack including a first ferromagnetic layer and a second ferromagnetic layer separated by a non-ferromagnetic interlayer, at least one first current line situated in the vicinity of the first magnetoresistive stack and generating in the vicinity of the first stack a magnetic field when an electric current passes through it, wherein, for said at least one first magnetoresistive stack, said first line includes at least two current input points such that two currents are added together in said first line, with a sum of both said currents being determined by said logic function, and wherein said first line is connected to at least one other current line belonging to a metallization level that is different from a metallization level of the first line, with both lines being connected by an interconnection conductive line and a point of connection between said interconnection line and said first line forming one of the two current input points.

2. A device according to claim 1 , wherein said at least two current input points are configured to inject respectively a current I 1 et I 2 into a third line such that the intensity, H′, of the field generated by said third line in the vicinity of the second layer is such that H ′ H = I 1 + I 2 I where H is the intensity of the magnetic field generated by the third current line when it has a current I passing through it.

3. A device according to claim 1 , including: at least one second magnetoresistive stack that may be either combined with said first stack or different from said first stack, with said second stack including a first ferromagnetic layer and a second ferromagnetic layer separated by a non-ferromagnetic interlayer; at least two current lines respectively belonging to a first and a second metallization level, with each of the two lines generating a magnetic field in the vicinity of said second stack when an electric current passes through them, said two lines being positioned at distances different from said second ferromagnetic layer of the second stack.

4. A device according to claim 3 , wherein said two lines are situated on either side of said second magnetoresistive stack.

5. A device according to claim 3 , wherein one of said two lines is situated at a distance d 1 above said second layer and the other of said two lines is situated at a distance d 2 below said second layer such that, for two currents of the same intensity flowing respectively in either of said two lines, the intensities H 1 and H 2 of the fields generated respectively by the line situated at distance d 1 and by the line situated at distance d 2 in the vicinity of said second layer are such that: H 1 H 2 = d 2 d 1 .

6. A device according to claim 1 , comprising: at least one magnetoresistive stack including a first ferromagnetic layer and a second ferromagnetic layer separated by a non-ferromagnetic interlayer; at least two current lines respectively belonging to a first and a second metallization level, with each of said lines generating a magnetic field in the vicinity of said at least one stack when an electric current passes through them, wherein said lines are positioned at an equal distance on either side of said second ferromagnetic layer.

7. A device according to claim 1 , wherein the first ferromagnetic layer is a hard ferromagnetic layer pinned in a fixed magnetic state used as a reference and the second ferromagnetic layer is a soft ferromagnetic layer.

8. A device according to claim 7 , wherein the soft layer has a circular or quasi-circular form so as to minimize the write-in current necessary to modulate their magnetic orientation.

9. A device according to claim 7 , wherein the hard layer of each of the magnetoresistive stacks is pinned in a magnetic state perpendicular to an axis of easy magnetization used as a reference for the soft layer of the same stack, with the soft layer of the magnetoresistive stack having a magnetic orientation that can be modulated by the current coming from the current line or current lines situated in the vicinity of the magnetoresistive stack so as to induce a modification to the transversal resistance of the stack sufficient to set off an electric signal, with such modulation of the magnetic orientation of the layer being sufficiently weak so that the orientation does not switch between two stable positions but fluctuates around one stable position.

10. A device according to claim 1 , comprising an input interface including: at least one input receiving logic information encoded in the form of a voltage level representing a logical ‘0’ or ‘1’; at least one output connected to an interconnection conductor line; electronic means for generating a current in said interconnection conductor line having a direction representative of the logic information, an absolute value of the intensity of said current being identical in either direction of said current.

11. A device according to claim 1 , comprising an output interface electrically linked to said at least one first magnetoresistive stack, with the interface comprising: an input connected to an interconnection conductive line electrically connecting said input to said at least one first magnetoresistive stack; means for measuring the current flowing through said at least first stack, with the current being representative of the magnetic state of said at least first stack; means for generating a voltage representative of said magnetic state according to said current.

12. A device according to claim 1 , comprising: a second magnetoresistive stack including a first ferromagnetic layer and a second ferromagnetic layer separated by a non-ferromagnetic interlayer; an output interface electrically connected to said first and second magnetoresistive stacks, said interface comprising: a first current input connected to an interconnection conductor line electrically connecting said first current input to said first magnetoresistive stack; a second current input connected to an interconnection conductor line electrically connecting said second input to said second magnetoresistive stack; means for generating a differential current (Aimed) between the current flowing in said first stack and the current flowing in said second stack when subjected to a bias voltage, said differential current being representative of a logic information; means for generating a voltage representative of said logic information according to said current differential.

13. A device according to claim 10 , wherein said input and/or output interface is performed in CMOS technology.

14. A device according to claim 13 , wherein said magnetic structure is situated above said interface or interfaces produced with CMOS technology.

15. A device according to claim 1 , wherein the non-ferromagnetic interlayer is made of magnesium oxide (MgO).

16. A device according to claim 1 , comprising at least two lines of different widths situated in the vicinity of a magnetoresistive stack.

17. An adder incorporating a device according claim 1 , the adder comprising: an input interface for signals of current I A , I B and I Cin flowing through three interconnection lines, a magnetic structure comprising: a magnetic part for generating a sum, a magnetic part for generating a carry, with said magnetic part for generating said carry comprising: a first magnetoresistive stack including a hard ferromagnetic layer and a soft ferromagnetic layer separated by a non-ferromagnetic interlayer, with the hard ferromagnetic layer being pinned in a fixed magnetic state used as a reference, a second magnetoresistive stack including a hard ferromagnetic layer and a soft ferromagnetic layer separated by a non-ferromagnetic interlayer, with the hard ferromagnetic layer being pinned in a fixed magnetic state used as a reference, a first current line generating a magnetic field in the vicinity of said first and second stacks and being situated at a distance d along a vertical axis of the soft layer of each of the first and third stacks, a first and a second vertical conductive via electrically connecting said first current line respectively to a second current line through which travels the current I A and to a branch of a third current line through which the sum of the currents I B +I Cin travel such that the currents I B +I Cin and I A are added together before being routed on said first current line generating a magnetic field in the vicinity of said first and second stacks.

18. An adder according to claim 17 , wherein the magnetic part for generating said sum comprises: a third magnetoresistive stack including a hard ferromagnetic layer and a soft ferromagnetic layer separated by a non-ferromagnetic interlayer, with the hard ferromagnetic layer being pinned in a fixed magnetic state used as a reference, a fourth magnetoresistive stack including a hard ferromagnetic layer and a soft ferromagnetic layer separated by a non-ferromagnetic interlayer, with the hard ferromagnetic layer being pinned in a fixed magnetic state used as a reference, a third and a fourth current line, said second, third and fourth current lines belonging respectively to a first, a second and a third metallization level, a third, a fourth and a fifth vertical conductive via for access to said input interface respectively electrically connected to said second, third and fourth current lines such that said third vertical via injects the current I B into said third line, said fourth vertical via injects the current I A into said second line and said fifth vertical via injects the current I Cin into said fourth current line, with said second current line generating a magnetic field in the vicinity of the third and fourth stack and being situated at a distance d along the vertical axis of the soft layer of each of said third and fourth stacks, with said third current line generating a magnetic field in the vicinity of said third stack and being situated at a distance 2×d along the vertical axis of the soft layer of said third stack, with said fourth current line generating a magnetic field in the vicinity of said third and fourth stacks and being situated at a distance 2×d along the vertical axis of the soft layer of each of said third and fourth stacks, with said third current line being electrically connected to said fourth current line by a vertical interconnection via such that the currents I B and I Cin of said third and fourth lines are added together before being routed on the branch of said fourth current line generating a magnetic field in the vicinity of said fourth stack, with said second current line being substantially perpendicular to said third and fourth current lines in the vicinity of said third stack and said second current line being substantially perpendicular to said fourth current line in the vicinity of said fourth stack.

19. An adder incorporating a device according to claim 1 , the adder comprising: an input interface for signals of current I A0 , I B0 and I Cin0 flowing through three interconnection lines, a magnetic structure comprising: a magnetic part for generating said sum comprising: a first magnetoresistive stack including a hard ferromagnetic layer and a soft ferromagnetic layer separated by a non-ferromagnetic interlayer, with the hard ferromagnetic layer being pinned in a fixed magnetic state used as a reference, a second magnetoresistive stack including a hard ferromagnetic layer and a soft ferromagnetic layer separated by a non-ferromagnetic interlayer, with the hard ferromagnetic layer being pinned in a fixed magnetic state used as a reference, a first, a second and a third current line belonging respectively to a first, a second and a third metallization level, a first, a second and a third vertical conductive via for accessing said input interface respectively electrically connected to said first, second and third current line such that the first vertical via injects the current I B0 into said first line, said second vertical via injects the current I A0 into said second line and said third vertical via injects the current I Cin0 into said third line, with said second current line generating a magnetic field in the vicinity of said first and second stacks and being situated at a distance d along the vertical axis of the soft layer of each of said first and second stacks, with said first current line generating a magnetic field in the vicinity of said first stack and being situated at a distance 2×d along the vertical axis of the soft layer of said first stack, with said third current line generating a magnetic field in the vicinity of said first and second stacks and being situated at a distance 2×d along the vertical axis of the soft layer of each of said first and second stacks, with said first current line being electrically connected to said third current line through a vertical interconnection via such that the currents I B0 and I Cin0 of said first and third lines are added together before being routed on branch of said third current line generating a magnetic field in the vicinity of said second stack, with said second current line being substantially perpendicular to said first and third current lines in the vicinity of said first stack and said second current line being substantially perpendicular to said third current line in the vicinity of said second stack, a fourth current line belonging to said first metallization level, a fourth and a fifth vertical conductive via electrically connecting said fourth current line respectively to said second current line through which the current I A0 travels and to said branch of said third current line through which travel the currents I B0 +I Cin0 such that the currents I B0 +I Cin0 and I A0 are added together before being routed on said fourth current line a fifth current line belonging to a metallization level different from said first metallization level and suitable for producing a magnetic field in the vicinity of a magnetoresistive stack, a sixth vertical conductive via electrically connecting said fourth current line to said fifth current line.

20. An adder according to claim 19 , comprising: a seventh vertical conductive via connected electrically to the fourth line; a current limiter circuit to limit the absolute value of the current flowing in said fourth line, with said current limiter circuit being connected to said propagation fourth line by said seventh conductive via.

21. An adder according to claim 20 , wherein said limiter circuit includes three transistors PMOS and three NMOS transistors mounted in series, with the first PMOS transistor and the third NMOS transistor having their common gate, the second PMOS transistor and the second NMOS transistor having their common gate, the third PMOS transistor and the first NMOS transistor having their common gate, with the common drain of the first NMOS transistor and of the third PMOS transistor being connected to said fourth line by said seventh vertical conductive via.

22. An “and” logic gate incorporating a device according to claim 1 , with said “and” gate including: an input interface for current signals I A and I B , a magnetic structure including: a magnetoresistive stack including a hard ferromagnetic layer and a soft ferromagnetic layer separated by a non-ferromagnetic interlayer, with the hard ferromagnetic layer being pinned in a fixed magnetic state used as a reference, a first, a second, a third and a fourth line current, with said first current line receiving the current I A , with said second current line receiving the current I B , with said third current line receiving a constant pre-determined current, with said fourth current line being situated in the vicinity of said magnetoresistive stack and generating in the vicinity of said stack a magnetic field when an electric current passes through it, with said fourth current line comprising three current input points electrically linking it to said first, second and third current lines such that the currents flowing in the first, second and third current lines are added together in said fourth line.

23. A majority voting circuit incorporating a device according to claim 1 , said majority voting circuit comprising: a current signal input interface for current I a , I b and I c flowing through three interconnection lines, a magnetic structure comprising a magnetic part for generating the output of said majority voting circuit including: a first magnetoresistive stack including a hard ferromagnetic layer and a soft: ferromagnetic layer separated by a non-ferromagnetic interlayer, with the hard ferromagnetic layer being pinned in a fixed magnetic, state used as a reference, a second magnetoresistive stack including a hard ferromagnetic layer and a soft ferromagnetic layer separated by a non-ferromagnetic interlayer, with the hard ferromagnetic layer being pinned in a fixed magnetic state used as a reference, a first current line generating a magnetic field in the vicinity of said first and second stacks and being situated at a distance d along the vertical axis of the soft layer of each of said first and third stacks, a first and a second vertical conductive via electrically connected to said first current line respectively to a second current line through which the current I a travels and to a branch of a third current line through which the sum of the currents I b +I c travels such that the currents I b +I c et I a are added together before being routed on said first current line generating a magnetic field in the vicinity of said first and second stacks.